Right to use side road

I bought 40 cents from a 80 cents plot in Cochin, Kerala. This 40 cents have a PWD road in the front side. The balance 40 cents is behind my property and a 5 mtrs side road is made to access the back side property. At the time of the deed, the original owner did not give me the right to use this side road as his idea was to use the back side 40 cents for his own use and the side road was supposed to be his private access. However, recently, the original owner has decided to sell out the back side 40 cents to other 3 parties and he has given the right to use the 5 mtrs side road to those 3 parties. Now the original owner have no more land left out from the original 80 cents. So requesting your advise, if i can also use this side road? or should i get a written permission from the original owner for right to use? Later, if i want to sell 10 cents from back side of my 40 cents, what should i do to give the right to use this side road to the next party? My email [deleted]